Patent GB-1187201-A (GB)
Title: Improvements in or relating to Door Latches.
Inventor: PICKARD PAUL ROBERT
IPC: E05B65/20
Filed: 1966-03-11
Abstract: 1,187,201. Door latches. WILMOT-BREEDEN Ltd. 8 March, 1967 [11 March, 1966], No. 10695/66. Heading E2A. A door latch comprises a rotary latch member 3 which is spring loaded towards an unlatching tripped position, a pawl member 13 retaining the latch member in the latching position by engagement of the pawl member with ratchet teeth 14, 15 associated with the latch member, the latch member having a recess for latching engagement with a keeper pin in a claw-like manner, the latch having a contactor lever 19 which engages the pawl member 13 to displace the latter for release of the latch member, a locking mechanism which in the operative position prevents external release of the latch and a projection 49 associated with the latch member which projection engages and displaces the contactor lever during movement of the latch member from the unlatching tripped position to the latching position with such displacement acting to return the locking mechanism to the inoperative position should that mechanism initially be in the operative position. In the construction shown the ratchet teeth are formed on a ratchet plate 10 mounted on a common shaft with the rotary latch member and the projection 49 is a peg which projects from the ratchet plate for engagement with an arm 22 of the contactor lever. The contactor lever has two other arms 19 and 20 the arm 19 having a projecting peg 23 which is engaged by a step 24 of a plate like stem 25 of a push button 26 during releasing movement of the push button, the resultant movement of the contactor lever 17 displacing the pawl member 13 which in turn releases the ratchet plate 10 so that the latch member 3 is turned by a spring 12 to the unlatching position. The arm 20 of the contactor lever can be moved upwardly with consequent release of the latch 3 by rotation of a bell-crank lever 32 connected through linkage 34 to an internal door handle. The locking mechanism comprises a U shaped locking lever 37, a second lever 43 and a link 44 which connects the two levers 37, 43. The lever 39 has a rectangular aperture 40 through which the free end 42 of the push button stem 25 passes, hence locking movement of the locking lever 37 turns the push button stem 25 to a position in which the step 24 is out of alignment with the peg 23 of the contactor lever so that it can no longer release the latch; in this position the stem 25 is blocked by engagement of a step 21 thereof with a turned-up lug 41 on a back plate 1 with which it is now aligned. Any attempt to force the latch by applying a hammer blow to the push button 26 merely bends the lug 41 so that the push button can move freely without being able to release the latch. The locking lever 43 has in its lower edge a cut-out slot 46 which in the locking position engages a turned up edge portion 47 of an arm 33 of the bell crank lever 32 this blocks releasing movement of the lever 32 so that both internal and external release of the latch is prevented. A cranked sill control rod 48 is connected to one arm 39 of the locking lever 40 so that it can be moved to-and-from locking position by the rod 48. Movement of the link 44 and hence of the two levers 37, 43 is controlled by over centre spring 45. If the door is closed with the locking mechanism operative the projection 49 engages the arm 22 of the contactor lever 17 as the latch member 3 is moved from the unlatching to the latching position; this turns the contactor lever in the releasing direction and the arm 20 of the contactor lever engages a projection 50 of the locking link 44 to displace the link upwardly so moving the lever 43 to the unlocking position. The keeper pin 7 has an end flange 52 to prevent separation of the keeper and latch longitudinally of the vehicle during a collision. A wedge block 53 fitted to a keeper back plate 8 engages a wedge reaction member 54 which also provides a bearing for the latch shaft 6, the engagement wedging the keeper pin 7 between claws 4 and 5 of the latch and providing vertical restraint which prevents door rattle.